The present teachings are predicated upon providing an improved parking brake for use in an existing disc brake system for use with vehicles. For example, the disc brake system may be used with almost any vehicle (e.g. car, truck, bus, train, airplane, or the like). Alternatively, the disc brake system may be integrated into assemblies used for manufacturing or other equipment that require a brake such as a lathe, winder for paper products or cloth, amusement park rides, wind turbines, or the like. However, the present teachings are most suitable for use with a passenger vehicle (e.g., a car, truck, sports utility vehicle, or the like).
Generally, a braking system includes a rotor, a caliper body, a support bracket, an inboard brake pad, and an outboard brake pad that are on opposing sides of the rotor. The caliper body further includes one or more fingers (with or without a piston), one or more piston bores, and a bridge that connects the one or more fingers to the piston bores or two opposing piston bores together. The piston bores each house a piston. The piston bores each have a bore axis that the pistons move along during a brake apply and a brake retract. The piston bores each include a fluid inlet, a closed wall, a front opening, and a cylindrical side wall that includes a seal groove located near the front opening. Typically, the fluid inlet is located in the closed wall of the piston bore so that when pressure is applied the fluid will flow into the piston bore. During a pressure apply the fluid will push the piston axially towards the front opening and into contact with a brake pad that generally includes a pressure plate and friction material and the friction material will contact the rotor on one side and an opposing brake pad will contact the rotor on an opposing side creating friction to stop rotation of the rotor and any component connected to the brake system. The brake pads may slide on an abutment along an axis of the pistons or the brake pads may include holes that receive pins and the brake pads may slide on pins that extend through the brake system so that a friction force may be created.
However, the braking system may be used in non-braking conditions when the vehicle is parked so that movement of the vehicle is prevented. The parking brake may be a discrete braking system or may use one or more components of a primary braking system. Parking brake systems typically include one or more brake pads and/or brake shoes that may be moved to create a parking force so that the vehicle is restrained during non-movement of a vehicle. These parking brake systems may be actuated by a cable that when moved biases a device that simultaneously actuates the brake pads and/or brake shoes to generate the parking force. More recently, there have been attempts to create a braking system that performs both the service braking and the parking braking.
Examples of braking systems and associated parking brake systems are disclosed in U.S. Pat. Nos. 5,090,518; 5,168,963; 6,450,586; and 6,488,132 and U.S. International Application Publication No. WO2016/015247 and WO2016/064980 all of which are expressly incorporated herein by reference for all purposes. It would be attractive to have a parking brake system that includes multiple discrete hydro-electrically actuated pistons that are simple in design and are capable of operating independently. It would be attractive to have a multiple piston corner module with the multiple pistons being part of separate brake assemblies (systems). What is needed is a process of controlling a plurality of discrete braking assemblies to coordinate and work together to create a service brake function, a parking brake function, or both. What is needed is multiple high efficiency brake assemblies that distribute work so that braking is performed without the need for a multiple piston caliper assembly. It would be attractive to have a multiple caliper system that work independently but cooperate with each other.